JP2006127797A - Microwave electrodeless discharge lamp device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave electrodeless discharge lamp device capable of restraining lowering of light-emitting efficiency of a discharge lamp. <P>SOLUTION: The microwave electrodeless discharge lamp device has a microwave oscillator generating microwave energy, a microwave resonator having a non-transmitting property against the microwave generated at the microwave oscillator, and a discharge lamp having a mercury reservoir installed inside and protruding outside the microwave resonator. A dielectric is arranged in a discharging space of the mercury reservoir making a cross section area of the discharging space small. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a microwave electrodeless discharge lamp apparatus.

As a conventional example of a microwave electrodeless discharge lamp device, for example, Japanese Patent No. 2512967
There are those shown in the Gazette. In this microwave discharge light source device, which includes a discharge tube in a microwave cavity, discharges the plasma medium in the discharge tube by microwaves, and emits the emitted light outside the microwave cavity, the tube of the discharge tube A part of the wall is exposed outside the microwave cavity, and a controller is provided to control the temperature of the part of the tube wall. With this configuration, a part of the tube wall of the discharge tube provided outside the microwave cavity is heated or cooled, and the mercury vapor pressure is optimally controlled to efficiently emit mercury resonance lines. It is stated that it can be done.
Japanese Patent No. 2512967 (pages 1 to 3)

  By the way, mercury and a buffer gas are generally enclosed in a microwave electrodeless discharge lamp. When the buffer gas reaches a predetermined value, the plasma in the discharge lamp easily spreads, so that the plasma enters the mercury reservoir and the mercury reservoir is heated. If a controller that controls the temperature of a part of the pipe wall is installed as in the conventional example above, the mercury reservoir temperature can be controlled to an appropriate value. There is a concern that the luminous efficiency of the discharge lamp may be reduced by excessively increasing the mercury vapor pressure by heating the reservoir.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a microwaveless electrode capable of suppressing a decrease in luminous efficiency of a discharge lamp when a temperature controller is not used. A discharge lamp device is provided.

  The invention according to claim 1 is a microwave oscillator that generates microwave energy, a microwave resonator that is impermeable to the microwave generated by the microwave oscillator, and a microwave installed in the microwave resonator. In a microwave electrodeless discharge lamp apparatus comprising a discharge lamp having a mercury reservoir protruding outside a wave resonator, a dielectric for reducing the discharge space cross-sectional area is installed in the discharge space of the mercury reservoir. To do.

  The invention according to claim 2 is characterized in that, in claim 1, the dielectric is made of an alumina glass fiber.

  The invention according to claim 3 is characterized in that, in the invention according to claim 1, a metal cylinder is provided around the mercury reservoir.

  The invention according to claim 4 is the invention according to claim 1, characterized in that at least a part of the mercury reservoir is formed so as to be substantially orthogonal to the axial direction of the discharge lamp.

  According to the present invention, by installing the dielectric for reducing the discharge space cross-sectional area in the discharge space of the mercury reservoir, the diffusion of the plasma into the mercury reservoir is suppressed, and the heating of the mercury reservoir by the plasma is suppressed. Thereby, it is possible to suppress a decrease in the luminous efficiency of the discharge lamp.

(First embodiment)
The present embodiment will be described with reference to FIGS. FIG. 1A is a cross-sectional view of the microwave electrodeless discharge lamp apparatus of the present embodiment, and FIG. 1B is a cross-section of the microwave resonator and the discharge lamp cut along XX ′ in FIG. FIG. FIG. 2 is a graph showing the relationship between the argon gas pressure enclosed in the discharge lamp and the diffusion plasma length.

  The microwave electrodeless discharge lamp apparatus according to the present embodiment includes a microwave oscillator 1 that generates a microwave and a guide that guides the microwave oscillated from the microwave oscillator 1 in a desired direction, as shown in FIG. A wave tube 2, a microwave resonator 3 that is impermeable to the microwave generated by the microwave oscillator 1, and a discharge lamp 4 installed in the microwave resonator 3 are provided. This will be specifically described below.

  The microwave oscillator 1 is composed of, for example, a magnetron that outputs a microwave having a frequency of 2.45 GHz, and a waveguide 2 that efficiently transmits the microwave oscillated from the microwave oscillator 1 in a desired direction at an output end thereof. Is connected. The waveguide 2 is also connected to the supply port 5 of the microwave resonator 3 that resonates with the microwave propagating in the waveguide 2. The microwave resonator 3 is a housing obtained by processing a metal plate, for example, and has a trapezoidal shape with an upper base of 107 mm, a lower base of 66 mm, and a height of 60 mm in the sectional view of FIG. That is, the length corresponding to the width of FIG. 1A is 540 mm. These dimensions are the conditions for a good lighting state with respect to the microwave of 2.45 GHz. The microwave resonator 3 has an opening 6 through which light is emitted above the paper surface of FIG. 1, and the opening 6 is covered with a mesh-like metal net 7. The metal mesh 7 is formed with a mesh size such that ultraviolet rays radiated from the discharge lamp 4 are transmitted but microwaves are not transmitted. A discharge lamp 4 that is lit by microwaves is installed inside the microwave resonator 3. The discharge lamp 4 is a straight tube type formed of quartz glass and having an outer diameter of 50 mm and a length of 500 mm. At both ends of the discharge lamp 4, mercury reservoirs 8 having a size of an outer diameter of 6 mm and a length of 60 mm and projecting horizontally with respect to the axial direction of the discharge lamp 4 and penetrating the microwave resonator 3 are formed. In the discharge space of the reservoir 8, an alumina glass fiber 10 which is a dielectric that reduces the discharge space cross-sectional area is provided. Further, mercury 9 and argon gas which is a rare gas are sealed in the discharge lamp 4.

  In the above configuration, when the microwave oscillator 3 irradiates the 2.45 GHz microwave toward the waveguide 2, the microwave irradiated to the waveguide 2 is transmitted through the supply port 5 to the microwave resonator 3. To be introduced. The microwave introduced into the microwave resonator 3 is reflected by the inner wall of the microwave resonator 3 and resonates to generate a standing wave. The electric field strength is highest at the antinodes of the standing wave, and the electric field generates a discharge in the discharge lamp 4, and 254 nm and 185 nm ultraviolet rays are emitted from the mercury excited by the generation of the discharge. The ultraviolet rays radiated from the discharge lamp 4 pass through the wire mesh 7 provided in the opening 6 of the microwave resonator 3 and are emitted to the outside.

Here, paying attention to the relationship between the length of the plasma generated by the discharge in the discharge lamp 4, that is, the diffusion plasma length, and the argon gas pressure, which is a rare gas, the argon gas pressure is 1 to 5 torr as shown in FIG. The length of the diffusion plasma increases in the range, and the maximum value is 70 mm when the argon gas pressure is 2 to 3 torr. That is, the plasma is easily diffused when the argon gas pressure is in the range of 1 to 5 torr. In this case, the plasma generated in the discharge lamp 4 tends to diffuse not only to the discharge lamp 4 but also to the mercury reservoir 8 portion, and the mercury reservoir 8 portion substantially reduces the cross-sectional area of the discharge space. When the alumina glass fiber 10 is installed, the electrons and ions constituting the plasma are recombined on the surface of the alumina glass fiber 10, and the diffusion of the plasma into the mercury reservoir 8 is suppressed. Thereby, heating of the mercury reservoir 8 by plasma can be prevented, and it is possible to suppress a decrease in luminous efficiency of the discharge lamp 4. Further, the mercury reservoir 8 penetrates the microwave resonator 3, and the discharge lamp 4 can be supported by the mercury reservoir 8.
(Second Embodiment)
A second embodiment will be described with reference to FIGS. FIG. 3 is a cross-sectional view of the microwave electrodeless discharge lamp device of the present embodiment. FIG. 4 is a cross-sectional view of a microwave electrodeless discharge lamp apparatus according to another example of the present embodiment.

  The microwave electrodeless discharge lamp device of this embodiment is different from that of the first embodiment in that a metal cylinder 11 covering the mercury reservoir 8 is provided around the mercury reservoir 8. The diameter of the metal cylinder 11 is 7 mm, which is slightly larger than the diameter of the mercury reservoir 8, and is electrically connected to the microwave resonator 3.

  Although the metal cylinder 11 can be regarded as a kind of waveguide, when the metal cylinder 11 is provided, a cutoff wavelength specific to the diameter of the metal cylinder 11 exists. That is, in the case of a microwave of 2.45 GHz, the metal cylinder 11 having a predetermined length with a diameter of 70 mm or less does not transmit the microwave. Thereby, the microwave which leaks from the circumference | surroundings of the mercury reservoir 8 becomes small, and can improve safety | security.

In addition, as shown in FIG. 4, by installing a cap-shaped metal body 12 that covers the mercury reservoir 8, diffusion of microwaves to the outside can be further suppressed. Here, when a metal mesh is used as the metal body 12, since the air passes through the metal mesh, the mercury reservoir 8 can be cooled.
(Third embodiment)
A third embodiment will be described with reference to FIGS. FIG. 5 is a cross-sectional view of the microwave electrodeless discharge lamp apparatus of the present embodiment. FIG. 6 is a cross-sectional view of another example of the microwave electrodeless discharge lamp apparatus according to this embodiment.

  This embodiment is different from the first embodiment in that a part or the whole of the mercury reservoir 8 is substantially orthogonal to the axis of the discharge lamp 4.

  Specifically, as shown in FIG. 5, a mercury reservoir 8 is provided on the side surface of the discharge lamp 4, that is, below the paper surface of FIG. 5, and the entire mercury reservoir 8 is substantially orthogonal to the axis of the discharge lamp 4. It is installed to do.

  Thereby, the plasma generated in the vicinity of the center of the discharge lamp 4 diffuses in the direction of both ends of the discharge lamp 4, but the mercury reservoir 8 is substantially orthogonal to the diffusion direction, so that the plasma is diffused. Will be hindered. That is, it becomes difficult for plasma to enter the mercury reservoir, thereby making it difficult for the mercury reservoir 8 to be heated.

  In FIG. 5, the mercury reservoir 8 is provided on the side surface of the discharge lamp 4. However, as shown in FIG. 6, the mercury reservoir 8 is provided at the end of the discharge lamp 4, and only the vicinity of the tip is used as the axis of the discharge lamp 4. Alternatively, it may be L-shaped orthogonal to the other.

  In the above embodiment, the alumina glass fiber 11 is used as the dielectric for reducing the discharge space sectional area. However, an alumina rod having a hole or a cylindrical quartz glass may be used. Further, although two mercury reservoirs 8 are provided, one mercury reservoir 8 may be provided. Furthermore, the mercury reservoir 8 may be installed at a position shifted from the central axis of the discharge lamp 4.

(A) is sectional drawing of the microwave electrodeless discharge lamp apparatus of this embodiment, (b) is sectional drawing of the microwave resonator cut | disconnected by XX 'of (a), and a discharge lamp. It is a graph which shows the relationship between the argon gas pressure enclosed in the discharge lamp, and diffusion plasma length. It is sectional drawing of the microwave electrodeless discharge lamp apparatus of 2nd Embodiment. It is sectional drawing of the microwave electrodeless discharge lamp apparatus which concerns on another example of 2nd Embodiment. It is sectional drawing of the microwave electrodeless discharge lamp apparatus of 3rd Embodiment. It is sectional drawing of the microwave electrodeless discharge lamp apparatus which concerns on another example of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microwave oscillator 2 Waveguide 3 Microwave resonator 4 Discharge lamp 5 Supply port 6 Opening 7 Wire mesh 8 Mercury reservoir 9 Mercury 10 Alumina glass fiber 11 Metal cylinder 12 Metal body

Claims (4)

A microwave oscillator that generates microwave energy, a microwave resonator that is impermeable to the microwave generated by the microwave oscillator, and a microwave resonator that is installed inside the microwave resonator and protrudes outside the microwave resonator A microwave electrodeless discharge lamp apparatus comprising a discharge lamp having a mercury reservoir, wherein a dielectric for reducing a sectional area of the discharge space is installed in a discharge space of the mercury reservoir. . 2. The microwave electrodeless discharge lamp device according to claim 1, wherein the dielectric is made of alumina glass fiber. 2. The microwave electrodeless discharge lamp apparatus according to claim 1, wherein a metal cylinder is provided around the mercury reservoir. 2. The microwave electrodeless discharge lamp device according to claim 1, wherein at least a part of the mercury reservoir is formed so as to be substantially orthogonal to the axial direction of the discharge lamp.

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